Federal Specification FF-L-2890B governs lock extensions and categorizes them as follows: pedestrian door preassembled locks (PDPL), pedestrian door lock assembly panic (PDLAP), and auxiliary deadbolts (ADB) for use with changeable combination locks and strikes. For each of these categories of extension, the specification defines types with key access control and types with keyless access control. Additionally, these extensions should be right and left hand interchangeable.
This invention was pursued to meet both the keyed and electronic access capabilities required per FF-26890B and be suitable for either right or left hand mounting. A single, reversible device with both access capabilities helps to optimize system design by minimizing components and packaging. The present invention can also be used in other high security lock applications where redundant access capabilities are desired.